Dataset Information

Induction of ganglioside synthesis in Drosophila brain accelerates assembly of amyloid ? protein.

ABSTRACT: The assembly and deposition of amyloid ? protein (A?) is a fundamental event during the early stages of Alzheimer's disease (AD) and cerebral amyloid angiopathy. A growing body of evidence indicates that gangliosides form a pathological platform for the generation of ganglioside-bound A?, which facilitates the assembly of soluble A?s; however, the molecular mechanisms underlying the binding of A? to gangliosides in the brain remain unclear due to the lack of an in vivo system that may address this issue. In insects, including the fruit fly Drosophila melanogaster, gangliosides are not intrinsically present at a detectable level. We herein demonstrate that ganglioside expression is inducible in Drosophila via the expression of transgenes of ganglioside synthesis enzymes and the feeding of exogenous sialic acid, and also that the induction of ganglioside synthesis significantly accelerates A? assembly in vivo. Our results support the hypothesis that gangliosides are responsible for A? assembly in vivo and also provide an opportunity to develop a valuable model for basic research as well as a therapeutic strategy for AD.

SUBMITTER: Yamasaki Y

PROVIDER: S-EPMC5974419 | biostudies-literature | 2018 May

REPOSITORIES: biostudies-literature

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Induction of ganglioside synthesis in Drosophila brain accelerates assembly of amyloid β protein.

Yamasaki Yasutoyo Y Tsuda Leo L Suzuki Akemi A Yanagisawa Katsuhiko K

Scientific reports 20180529 1

The assembly and deposition of amyloid β protein (Aβ) is a fundamental event during the early stages of Alzheimer's disease (AD) and cerebral amyloid angiopathy. A growing body of evidence indicates that gangliosides form a pathological platform for the generation of ganglioside-bound Aβ, which facilitates the assembly of soluble Aβs; however, the molecular mechanisms underlying the binding of Aβ to gangliosides in the brain remain unclear due to the lack of an in vivo system that may address th ...[more]

PMID: 29844375

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Project description:Gangliosides are important players for controlling neuronal function and are directly involved in AD pathology. They are among the most potent stimulators of A? production, are enriched in amyloid plaques and bind amyloid beta (A?). However, the molecular mechanisms linking gangliosides with AD are unknown. Here we identified the previously unknown function of the amyloid precursor protein (APP), specifically its cleavage products A? and the APP intracellular domain (AICD), of regulating GD3-synthase (GD3S). Since GD3S is the key enzyme converting a- to b-series gangliosides, it therefore plays a major role in controlling the levels of major brain gangliosides. This regulation occurs by two separate and additive mechanisms. The first mechanism directly targets the enzymatic activity of GD3S: Upon binding of A? to the ganglioside GM3, the immediate substrate of the GD3S, enzymatic turnover of GM3 by GD3S was strongly reduced. The second mechanism targets GD3S expression. APP cleavage results, in addition to A? release, in the release of AICD, a known candidate for gene transcriptional regulation. AICD strongly down regulated GD3S transcription and knock-in of an AICD deletion mutant of APP in vivo, or knock-down of Fe65 in neuroblastoma cells, was sufficient to abrogate normal GD3S functionality. Equally, knock-out of the presenilin genes, presenilin 1 and presenilin 2, essential for A? and AICD production, or of APP itself, increased GD3S activity and expression and consequently resulted in a major shift of a- to b-series gangliosides. In addition to GD3S regulation by APP processing, gangliosides in turn altered APP cleavage. GM3 decreased, whereas the ganglioside GD3, the GD3S product, increased A? production, resulting in a regulatory feedback cycle, directly linking ganglioside metabolism with APP processing and A? generation. A central aspect of this homeostatic control is the reduction of GD3S activity via an A?-GM3 complex and AICD-mediated repression of GD3S transcription.

Dataset Information

Induction of ganglioside synthesis in Drosophila brain accelerates assembly of amyloid ? protein.

Publications

Induction of ganglioside synthesis in Drosophila brain accelerates assembly of amyloid β protein.

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